1. Field of the Invention
The present invention pertains to energy conversion, and more particularly to apparatus that converts wind energy into mechanical or electrical energy.
2. Description of the Related Art
It has long been known to harness the wind to perform useful work. For example, sailboats and water-pumping windmills have been in use for centuries.
Many wind powered machines utilize blades that are fixed to a supporting frame. Those types of machines typically have an axis of rotation for the blades and frame that is generally parallel to the direction of wind flow. In that case, the blades rotate in a plane that is perpendicular to the direction of the wind. Another type of wind machine utilizes a frame that rotates about an axis that is perpendicular to the wind direction. In that type of machine, the blades are not fixed to the supporting frame. Rather, the blades pivot such that the wind strikes the blades' full areas so as to push the blades against the frame when the blades move in the same direction as the wind. The blades pivot such that the wind passes through them when the blades move in the opposite direction as the wind.
Some specific applications of prior attempts to convert wind energy into mechanical energy by using pivotable blades may be seen in U.S. Pat. Nos. 23,932; 41,442; 1,753,302; 2,006,024; 2,129,652; 4,408,955; and 4,649,284. U.S. patent publication 2002/0187038 shows similar apparatus. U.S. Pat. Nos. 4,134,710 and 5,525,037 disclose prior machines that convert wind energy into electricity.
U.S. Pat. No. 3,920,354 teaches a wind machine in which the blades are hinged to a series of mutually perpendicular wires. In turn, the wires are part of a frame that rotates about an axis of rotation. A similar design is shown in U.S. Pat. No. 4,684,817 and United Kingdom patent application GB2048391. The wire and blade design of the two foregoing U.S. patents and the United Kingdom patent application suffer the disadvantage of having the wires integral with the frame. That is, the ends of the wires are permanently fixed directly to the associated machine frame component. Consequently, the assembly of the blades to the wires can be achieved only in the presence of the frame. Such assembly is often awkward. Further, if a blade or wire is damaged, the entire machine is out of operation while repairs are made.
Thus, a need exists for improvements to wind machines.